MFC RTTI

先放上分析后，并且简化后的源代码，有时间在说

 1 #include  < stdio.h >
 2 #define  LPCSTR char *
 3 #define  BOOL bool
 4 #define  TRUE true
 5 #define  FALSE false
 6 #define  NULL 0
 7
 8 struct  CRuntimeClass
 9 {
10    // Attributes
11    LPCSTR m_lpszClassName;
12    int m_nObjectSize;
13    
14    BOOL IsDerivedFrom(const CRuntimeClass* pBaseClass) const
15    {
16        // simple SI case
17        const CRuntimeClass* pClassThis = this;
18        while (pClassThis != NULL)
19        {
20            if (pClassThis == pBaseClass)
21                return TRUE;
22            pClassThis = pClassThis->m_pBaseClass;
23        }
24        return FALSE;       // walked to the top, no match
25    }
26    
27    void PrintAll()
28    {
29        for(CRuntimeClass * pc=this; pc; pc=pc->m_pBaseClass)
30        {
31            printf("->%s", pc->m_lpszClassName);
32        }
33        printf("\n");
34    }
35    CRuntimeClass* m_pBaseClass;       // linked list of registered classes
36} ;
37
38
39 #define  RUNTIME_CLASS(class_name) ((CRuntimeClass*)(&class_name::class##class_name))
40
41 class  CObject
42 {
43public:
44    static CRuntimeClass classCObject;         
45    
46    virtual CRuntimeClass * GetRuntimeClass() const    //must be virtual
47    {
48        return &CObject::classCObject;
49    }
50    
51    BOOL IsKindOf(const CRuntimeClass* pClass) const
52    {
53        CRuntimeClass* pClassThis = GetRuntimeClass();
54
55        return pClassThis->IsDerivedFrom(pClass);
56    }
57    
58} ;
59
60 __declspec(selectany) CRuntimeClass CObject::classCObject  =      
61 {     
62    "CObject", sizeof(class CObject), NULL    
63} ;     
64
65 class  A: public  CObject
66 {
67    public:     
68        static const CRuntimeClass classA;         
69        virtual CRuntimeClass* GetRuntimeClass() const;        
70} ;
71
72 __declspec(selectany)  const  CRuntimeClass A::classA  =      
73 {     
74    "A", sizeof(class A), &CObject::classCObject     
75} ;     
76 CRuntimeClass *  A::GetRuntimeClass()  const      
77 { return ((CRuntimeClass*)(&A::classA)); }         
78
79 void  main()
80 {
81    A a;
82    printf("%d\n", a.IsKindOf(RUNTIME_CLASS(CObject)));
83    printf("%d\n", a.IsKindOf(RUNTIME_CLASS(A)));
84    //printf("%d\n", a.IsKindOf(RUNTIME_CLASS(int)));    //Compile Fail
85    
86    RUNTIME_CLASS(CObject)->PrintAll();
87    RUNTIME_CLASS(A)->PrintAll();
88}